Jenna McMurray, QMI Agency

CALGARY — Lethbridge, Alta., police are investigating but don't plan to lay charges after a teen's arm was crushed under a school bus in a "freak accident" Monday morning.

At about 7:20 a.m., the bus stopped to pick up some students. As the 68-year-old male driver began pulling away from the curb slowly, a 16-year-old girl ran from a nearby alley, hoping to catch the bus, police said.

"She was banging on the side, trying to get the driver's attention," police spokeswoman Kristen Harding said.

In the process, the teen fell into the gutter on the road and the bus drove onto her arm.

The driver stopped and opened the door to find the girl pinned underneath.